Core Block Research Articles

Identifying Young Diagrams Among Residue Multisets

To any Young diagram we can associate the multiset of residues of all its nodes. This paper is concerned with the inverse problem: given a multiset of elements of $$\mathbb {Z}/e\mathbb {Z}$$ , does it comes from a Young diagram? We give a full solution in level one and a partial answer in higher levels for Young multidiagrams, using Fayers’s notions of core block and weight of a multipartition. We apply the result in level one to study a shift operation on partitions.

Preliminary Neutronics Design and Analysis of the Fast Modular Reactor

General Atomics is developing a new 100-MW(thermal) fast modular reactor (FMR) that provides safe, carbon-free electricity and is capable of incremental capacity additions. The modular design allows it to be factory built and assembled onsite to keep the capital cost low, while the use of dry cooling facilitates siting to complement renewables in nearly any location. The FMR uses high-assay low-enriched uranium-dioxide fuel encapsulated by recognized irradiation-resistant silicon carbide composite (SiGA®) cladding that is derisked in the current accident-tolerant fuel program. The FMR fuel assembly is a hexagonal fuel bundle of 120 fuel rods. The total length of the fuel assembly is less than 4 m, with an active fuel length of 1.8 m. The fuel assemblies are configured in an annular core that is located and supported by the reactor internals. The coolant material is helium at a normal operating pressure of 7 MPa. The core is surrounded by zirconium silicide (Zr3Si2) and graphite reflector blocks. The fuel, coolant, internals, and reflectors are contained within a reactor pressure vessel. The preliminary nuclear design and analysis established the arrangement of the active core and reflector blocks. The nuclear design analyses of the FMR defined the design parameters, such as fuel enrichments, excess reactivity, fueling scheme, fuel cycle, power distribution, and control rod worth. The preliminary conceptual design determined the three-batch fueling scheme with the allowable total power peaking factor of 1.5. The average discharge burnup is 100 GW days per ton of uranium.

High Temperature Test Facility sensitivity and calibration studies to inform OECD-NEA benchmark calculations

The High Temperature Test Facility (HTTF) is a thermal hydraulics test facility for block-type high-temperature gas-cooled reactors (HTGRs) built to provide data to validate HTGR modeling tools. Several experiments were conducted at HTTF in the spring of 2019 that serve as the basis for an upcoming Organization for Economic Cooperation and Development – Nuclear Energy Agency HTGR thermal hydraulics benchmark. We present sensitivity studies of steady state and both the pressurized and depressurized conduction cooldown (PCC and DCC) transients in HTTF in this paper. These studies identified that uncertainties in the thermal conductivity of the ceramic blocks making up the HTTF core are significant drivers of peak temperatures in steady state, PCC, and DCC. The emissivity of the heater rods and core blocks also provide significant control over heater rod temperatures. We also performed calibration studies based on HTTF Experiment PG-26, which was intended to serve as the basis for the DCC benchmark problem. We found that no calibration was able to reproduce PG-26 peak block temperatures within an average of 30%, but by taking the best-estimate PG-26 calibration and applying it to a similar experiment—PG-29—we were able to reproduce the peak block temperatures within an average of 6.2% error. Based on this nearly fivefold improvement in peak block temperature predictions from PG-26 to PG-29 and confounding factors in PG-26 that contributed to previous difficulties modeling the experiment in RELAP5-3D and SAM we conclude that PG-26 data are insufficient for developing a DCC benchmark and recommend using PG-29 as the benchmark experiment instead.

Encapsulation of phenylacetic acid in block copolymer nanoparticles during polymerization induced self‐assembly

AbstractPolymerization induced self‐assembly (PISA) is an in situ method for producing block copolymer nanoparticles. Performing PISA in the presence of a pharmaceutical drug causes the nanoparticles to encapsulate the drug. While this approach is straightforward, the effects of drug loading and block copolymer composition remain unclear. Here, we investigate encapsulation of the drug phenylacetic acid (PA) in poly(glycerol monomethacrylate)‐block‐poly(2‐hydroxypropyl methacrylate) (PGMA‐PHPMA) nanoparticles during PISA. Nanoparticle morphology is characterized by electron microscopy and light scattering, while encapsulation efficiency () is quantified using nuclear magnetic resonance diffusometry. Increasing the PA loading shifts the nanoparticle morphology from spherical micelles cylindrical micelles vesicles. At a 32 mg/ml PA loading, maximizes at ~80%. Increasing the PHPMA degree of polymerization minimally impacts . The invariance of toward core block length suggests that PA binds to the nanoparticle corona, highlighting the importance of the hydrophilic block for drug encapsulation during PISA.

Polyferrocenylsilane Block Copolymer Spherulites in Dilute Solution

Self-assembly of block copolymers (BCP) into uniform 3D structures in solution is an extremely rare phenomenon. Furthermore, the investigation of general prerequisites for fabricating a specific uniform 3D structure remains unknown and challenging. Here, through a simple one-pot direct self-assembly (heating and cooling) protocol, we show that uniform spherulite-like structures and their precursors can be prepared with various poly(ferrocenyldimethylsilane) (PFS) BCPs in a variety of polar and non-polar solvents. These structures all evolve from elongated lamellae into hedrites, sheaf-like micelles, and finally spherulites as the annealing temperature and supersaturation degree are increased. The key feature leading to this growth trajectory is the formation of secondary crystals by self-nucleation on the surface of early-elongated lamellae. We identified general prerequisites for fabricating PFS BCP spherulites in solution. These include corona/PFS core block ratios in the range of 1-5.5 that favor the formation of 2D structures as well as the development of secondary crystals on the basal faces of platelets at early stages of the self-assembly. The one-pot direct self-assembly provides a general protocol to form uniform spherulites and their precursors consisting of PFS BCPs that match these prerequisites. In addition, we show that manipulation of various steps in the direct self-assembly protocol can regulate the size and shape of the structures formed. These general concepts show promise for the fabrication and optimization of spherulites and their precursors from semicrystalline BCPs with interesting optical, electronic, or biomedical properties using the one-pot direct self-assembly protocol.

Разработка микроконтроллерного FMU ядра на базе ПЛИС для научной космической аппаратуры

A FMU (Flexible Microcontroller Unit) model of the core of a domestic FPGA is proposed with the purpose of obtaining characteristics superior in speed and type of data processing over modern domestic and foreign microcontrollers. The FMU core and its corresponding peripherals are designed on FPGA, which makes the architecture of the entire microcontroller flexible and allows its characteristics to be varied without the need to acquire other chips. The entire architecture is a single configuration file, written in the Verilog HDL and combining the core and peripheral blocks. At the request of the user, the number of peripheral modules сan be either increased or reduced. Parallel (multicore) data processing is also available, which function is absent in modern microcontrollers. The program for the configured microcontroller is written in a C-style language, which is converted into a binary package of a program loaded separately into the program memory of the microcontroller in question. To convert the source code into such a package, a corresponding C++ compiler was developed. The paper provides a block diagram of the kernel architecture, time diagrams of various packages and instructions, as well as a list of kernel commands. The test results presented in the paper demonstrate small time expenditures on executing some instructions for working with internal and external RAM. Conclusions are formulated and brief characteristics of the core are given.

Analysis on heat transfer performance sub-channels of sodium-cooled fast reactor fuel assemblies based on entransy

In this paper, the symmetric heat transfer performance of sodium-cooled fast reactor fuel assemblies was analyzed and studied. The model is analytically optimized based on sub-channel calculations. The deviations of the numerical simulation results from the pre-existing experimental data in the literature are within 10 %, with an average deviation of 2.5 %, which tested the reliability of the model. The calculated results demonstrated that the distribution of the axial power, temperature, and coolant of the reactor core is approximately symmetric M-shape. The reactor core coolant has a monotonic increase in axial distribution with the cladding temperature and the temperature peaks all appear at the reactor core outlet. The individual fuel assemblies' internal temperature is relatively sensitive to the axial power distribution, and there are troughs around the imports and exports. The simulated results showed that the center temperature of the hottest rod reactor core block reached 965.65 K. This pa- per provides a better guide to understanding the overall heat transfer effect by optimizing the heat transfer model.

TC-Net: A Modest & Lightweight Emotion Recognition System Using Temporal Convolution Network

Speech signals play an essential role in communication and provide an efficient way to exchange information between humans and machines. Speech Emotion Recognition (SER) is one of the critical sources for human evaluation, which is applicable in many real-world applications such as healthcare, call centers, robotics, safety, and virtual reality. This work developed a novel TCN-based emotion recognition system using speech signals through a spatial-temporal convolution network to recognize the speaker’s emotional state. The authors designed a Temporal Convolutional Network (TCN) core block to recognize long-term dependencies in speech signals and then feed these temporal cues to a dense network to fuse the spatial features and recognize global information for final classification. The proposed network extracts valid sequential cues automatically from speech signals, which performed better than state-of-the-art (SOTA) and traditional machine learning algorithms. Results of the proposed method show a high recognition rate compared with SOTA methods. The final unweighted accuracy of 80.84%, and 92.31%, for interactive emotional dyadic motion captures (IEMOCAP) and berlin emotional dataset (EMO-DB), indicate the robustness and efficiency of the designed model.

Modern Tendencies in Vehicle-Based Condition Monitoring of the Railway Track

Condition Monitoring (CM) describes the continuous observation of a dynamical system or process in order to track the evolution of its state and to detect signs of faults in an early stage. It constitutes the core block for performing fault diagnosis and prognosis, allowing a condition-based assessment of the system and supporting the implementation of an intelligent, cost-effective maintenance policy. This study focuses on the vehicle-based monitoring of railway infrastructure. First, the main concepts related to intelligent maintenance systems and strategies are depicted in a general framework. Later on, the specific application, the railway track-vehicle interaction system, is introduced. Railway vehicle instrumentation for track condition monitoring is analysed, with a special focus on the inertial measurement systems. A review of the processing algorithms used for railway monitoring is done and a taxonomy is proposed, based on the methodology approach: model-based, data-driven or hybrid. An analysis on the monitoring algorithms according to the geographical region is also made. It has been found that the railway vocation of each individual region determines the monitoring objectives pursued, as well as the methodological approach and the specific algorithms used. Finally, current trends and research gaps in railway monitoring are identified and outlined.

Tuning conformational asymmetry in particle-forming diblock copolymer alloys.

Self-consistent field theory is employed to compute the phase behavior of binary blends of conformationally asymmetric, micelle-forming diblock copolymers with miscible corona blocks and immiscible core blocks (a diblock copolymer "alloy"). The calculations focus on establishing conditions that promote the formation of Laves phases by tuning the relative softness of the cores of the two different Laves phase particles via independent control of their conformational asymmetries. Increasing the conformational asymmetry of the more spherical particles of the Laves structure has a stabilizing effect, consistent with the expectations of increased imprinting of the Wigner-Seitz cells on the core/corona interface as conformational asymmetry increases. The resulting phase diagram in the temperature-blend composition space features a more stable Laves phase field than that predicted for conformationally symmetric systems. The phase field closes at low temperatures in favor of macrophase separation between a hexagonally-packed cylinder (hex) phase and a body-centered cubic phase. Companion calculations, using an alloy whose components do not produce a hex phase in the neat melt state, suggest that the Laves phase field in such a blend will persist at strong segregation.

Dual Thermo- and pH-Responsive N-Cyanomethylacrylamide-Based Nano-Objects Prepared by RAFT-Mediated Aqueous Polymerization-Induced Self-Assembly

We report the straightforward synthesis of dual stimuli-responsive nano-objects using a RAFT-mediated polymerization-induced self-assembly process in water. The key to complex and tunable responsiveness was the copolymerization of N-cyanomethylacrylamide, providing upper critical solution temperature-type polymers, with a pH-sensitive monomer (acrylic acid, AA). Not only the core block length but also the AA content and slight changes in the degree of ionization of AA in the polymerization medium (αAA,0) had a great impact on the particle morphology. Generally, higher AA contents favored the formation of spherical nano-objects, while low αAA,0 led to higher-order morphologies. We demonstrated that the nano-objects exhibited a complex dual responsiveness to changes in the degree of ionization and temperature. Progressively increasing post-polymerization the degree of ionization of the AA units incorporated in the copolymer (αAA) triggered morphological transitions. Remarkably, a single copolymer composition formed well-defined vesicles, worms, and spheres that eventually dissociated into individual chains. Temperature-dependent small-angle X-ray scattering analyses evidenced a complex thermo-responsive behavior, which depended on the copolymer composition and αAA. For some compositions, we observed both a cloud point and a clearing point, attributed to the formation of secondary aggregates and chain dissolution, respectively.

FPGA design of arithmetic optimised APT-VDF using reusable Vedic multiplier with simplified combinational logics for medical signal denoising

ABSTRACT All-pass transformation (APT)-based variable digital filters (VDFs) can be used in different biomedical signal-processing applications, particularly in electrocardiograph denoising. In this paper, arithmetic optimised APT-VDF is proposed by modifying the hardware structure of APT-VDF based on arithmetic perception to enhance the performance in terms of area, speed and power consumption. The core blocks of the suggested Arithmetic Optimised APT-VDF (AOAPT-VDF)are adders and multipliers. This paper introduces a new reusable Vedic multiplier with redundant detection unit to identify redundant computations while generating the partial products. Also, a new Carry select adder (CSLA) with simplified combinational logics is proposed to improve the performance of the CSLA by simplifying the partial sum and carry generation logics without requiring Ripple Carry Adders. The proposed Reusable Vedic Multiplier with Redundant Detection Logic (RVM-RDL) also reuses the same vertical and cross-product generation units repetitively to reduce the area while increasing the bit length. The effectiveness of the suggested AOAPT is analysed utilising the MIT-BIH Arrhythmia Database. The proposed AOAPT-VDF consumes only 0.21 W power and achieves a 235.50 MHz operating frequency.

Fundamentals of Industrial Strategizing: Formation of the Concept

The dynamism of the economic environment, associated with a change in the group of strategic factors and the resource base, leads to a forced reduction in the required time to search for and justify strategic decisions regarding the implementation of cardinal opportunities, while the cost of a mistake increases. In this context, the choice and justification of the long-term vector and the object development trajectory, which corresponds to the process of developing and further implementing the strategy, acquires the highest importance. It becomes necessary to know and apply verified and reasonable approaches to strategizing, on the contrary, the lack of understanding or the use of approaches and tools that do not meet the requirements can lead to methodological errors that have long-term negative consequences for the strategizing object. In turn, industries are one of the prospective strategizing objects, and it is they who are able to act as drivers for the development of economic systems as a whole. In order to eliminate errors and reduce impractical and methodologically incorrect documents on industrial development that do not have a strategic character, it is proposed to systematize and clearly regulate the sequence of industrial strategizing, which is the purpose of this scientific study. Since the most critical errors occur at the initial stages of strategizing, to a greater extent this research is focused on the formation of the concept — the core block of any strategy. In accordance with this, the scientific article presents the main stages of industry strategizing, describes in detail the essence and procedure for the formation of the concept of industry strategy.

Fundamental physics distinguishes the initial stage acoustic emission (AE) behavior between compressive and fracture toughness tests in rock

We resolve a misunderstanding on the general observation of AE releases from mode-I and mixed-mode fracture toughness tests, and from compression tests on rock core or prismatic blocks. The fracture toughness tests expect few early AE while the compression test expects many. We investigate the detailed AE energy release organization from two novel approaches. From a system’s perspective, the former (mode-I and mixed-mode) undergoes a process of continuous entropy increase from the well-organized global condition regardless of having continuous energy input; the latter (rock core compression) displays a process of continuous entropy decrease until macroscale rock fracture formation. From perspective of elementary-damage-accumulation, the dynamic building process of the AE topology network from the mode-I or mixed-mode test displays a significantly stronger triggering effect compared to the rock core compression—especially in the early stages of these tests. Observations from both aspects consistently suggest the two types of rock fracture processes are of different physical processes. The analogue of the mode-I and mixed-mode fracture toughness tests is the pervasive process, while that of the rock core or prismatic block compression is the site percolation process. The pervasive source of the mode-I and mixed-mode tests provides a significantly lower energy barrier for the rock fracture formation than the rock core or prismatic block compression. Consequently, its early-stage AE releases will be suppressed or eliminated. Investigating the scaling features of the AE releases suggests the observational features for a notch-induced rock fracture process are universal across scale.

Static CMOS Physically Unclonable Function Based on 4T Voltage Divider With 0.6%–1.5% Bit Instability at 0.4–1.8 V Operation in 180 nm

This article introduces a novel class of static and monostable CMOS physically unclonable functions (PUFs) for hardware security applications. The PUF bitcell is based on a sub-threshold four-transistor (4T) voltage divider as the core block, along with an inverter as the output stage. The 4T voltage divider consists of two series-connected and nominally identical PMOS-only two-transistor (2T) circuits. This allows inherently random bit generation assisted by mismatch while also ensuring inherent robustness against environmental variations. A 180-nm test chip was characterized to validate our solution. Measurements of the 4T bitcell core prove its capability to generate random voltages with high dispersion (i.e., close to either ground or supply voltage levels) and high stability across a wide range of environmental conditions. The statistical PUF performance was evaluated on an <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$8\times32$ </tex-math></inline-formula> bitcell array without applying any post-silicon stability-enhancement technique. Raw measurements reveal a bit instability of only ~0.6% at golden key (GK) conditions (1.8 V and 25 °C), which increases up to 1.5% at 0.4 V and room temperature. When compared to prior art, our solution shows competitive performance in terms of stability, uniqueness (mean normalized inter-PUF Hamming distance (HD) of 0.493), and reproducibility (mean normalized intra-PUF HD of 0.0016), at the cost of more area-hungry design (~7200-F <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> bitcell area).

Real-time MRI motion estimation through an unsupervised k-space-driven deformable registration network (KS-RegNet)

Purpose. Real-time three-dimensional (3D) magnetic resonance (MR) imaging is challenging because of slow MR signal acquisition, leading to highly under-sampled k-space data. Here, we proposed a deep learning-based, k-space-driven deformable registration network (KS-RegNet) for real-time 3D MR imaging. By incorporating prior information, KS-RegNet performs a deformable image registration between a fully-sampled prior image and on-board images acquired from highly-under-sampled k-space data, to generate high-quality on-board images for real-time motion tracking. Methods. KS-RegNet is an end-to-end, unsupervised network consisting of an input data generation block, a subsequent U-Net core block, and following operations to compute data fidelity and regularization losses. The input data involved a fully-sampled, complex-valued prior image, and the k-space data of an on-board, real-time MR image (MRI). From the k-space data, under-sampled real-time MRI was reconstructed by the data generation block to input into the U-Net core. In addition, to train the U-Net core to learn the under-sampling artifacts, the k-space data of the prior image was intentionally under-sampled using the same readout trajectory as the real-time MRI, and reconstructed to serve an additional input. The U-Net core predicted a deformation vector field that deforms the prior MRI to on-board real-time MRI. To avoid adverse effects of quantifying image similarity on the artifacts-ridden images, the data fidelity loss of deformation was evaluated directly in k-space. Results. Compared with Elastix and other deep learning network architectures, KS-RegNet demonstrated better and more stable performance. The average (±s.d.) DICE coefficients of KS-RegNet on a cardiac dataset for the 5- , 9- , and 13-spoke k-space acquisitions were 0.884 ± 0.025, 0.889 ± 0.024, and 0.894 ± 0.022, respectively; and the corresponding average (±s.d.) center-of-mass errors (COMEs) were 1.21 ± 1.09, 1.29 ± 1.22, and 1.01 ± 0.86 mm, respectively. KS-RegNet also provided the best performance on an abdominal dataset. Conclusion. KS-RegNet allows real-time MRI generation with sub-second latency. It enables potential real-time MR-guided soft tissue tracking, tumor localization, and radiotherapy plan adaptation.

Nonnuclear Experimental Capabilities to Support Design, Development, and Demonstration of Microreactors

This work provides a summary of selected experimental capabilities being developed to support nonnuclear testing and demonstration of technology in support of microreactors under the U.S. Department of Energy’s (DOE’s) Microreactor Program. Major capabilities include the Single Primary Heat Extraction and Removal Emulator (SPHERE) and the Microreactor Agile Non-nuclear Experimental Test Bed (MAGNET). The SPHERE facility allows for controlled testing of the steady-state and transient heat rejection capabilities of a single heat pipe using electrical heaters that simulate nuclear heating. The facility is capable of monitoring axial temperature profiles along the heat pipe and surrounding test articles during startup, steady-state operation, and transients. Instrumentation includes noncontact infrared thermal imaging, surface thermocouples, spatially distributed fiber optic temperature and strain sensors, electrical power meters, and a water-cooled, gas-gap calorimeter for quantifying heat rejection from the heat pipe. The facility can be operated under both vacuum and inert-gas conditions. The MAGNET facility is a large-scale, 250-kW electrically heated microreactor test bed to enable nonnuclear experimental evaluation of a variety of microreactor concepts. It can be supplied to electrically heat a scaled section of a microreactor and further test the capabilities of heat rejection systems. The initial MAGNET experiments will support technology maturation and reduce uncertainty and risk associated with the design, operation, and deployment of monolithic heat pipe–based reactors. However, this test bed can broadly be applied to multiple microreactor concepts to evaluate a wide range of thermal-hydraulic and structural phenomena such as interface coupling with power conversion units and other collocated systems. MAGNET can evaluate integral thermomechanical effects during electrical heating of an array of heat pipes in a larger test article. Examples of initial testing will include thermal stresses in the monolith and the impact of debonding of a heat pipe from the core block and how that failure could impact surrounding heat pipes, i.e., understanding the potential for cascading failure. This work also discusses some modeling capabilities that can support experiment design, analysis, and interpretation, including the heat pipe code Sockeye and a comparison of thermal-structural simulations performed using ABAQUS and STAR-CCM+.

Truncating fined-tuned vision-based models to lightweight deployable diagnostic tools for SARS-CoV-2 infected chest X-rays and CT-scans.

In such a brief period, the recent coronavirus (COVID-19) already infected large populations worldwide. Diagnosing an infected individual requires a Real-Time Polymerase Chain Reaction (RT-PCR) test, which can become expensive and limited in most developing countries, making them rely on alternatives like Chest X-Rays (CXR) or Computerized Tomography (CT) scans. However, results from these imaging approaches radiated confusion for medical experts due to their similarities with other diseases like pneumonia. Other solutions based on Deep Convolutional Neural Network (DCNN) recently improved and automated the diagnosis of COVID-19 from CXRs and CT scans. However, upon examination, most proposed studies focused primarily on accuracy rather than deployment and reproduction, which may cause them to become difficult to reproduce and implement in locations with inadequate computing resources. Therefore, instead of focusing only on accuracy, this work investigated the effects of parameter reduction through a proposed truncation method and analyzed its effects. Various DCNNs had their architectures truncated, which retained only their initial core block, reducing their parameter sizes to <1 M. Once trained and validated, findings have shown that a DCNN with robust layer aggregations like the InceptionResNetV2 had less vulnerability to the adverse effects of the proposed truncation. The results also showed that from its full-length size of 55 M with 98.67% accuracy, the proposed truncation reduced its parameters to only 441 K and still attained an accuracy of 97.41%, outperforming other studies based on its size to performance ratio.

Molecular Characterization of Polar Compounds in Crude Oil Affecting Sandstone Wettability Revealed by Fourier Transform-Ion Cyclotron Resonance-Mass Spectrometry

Summary Knowing the composition, molecular size, and structure of polar compounds in crude oil that affect sandstone wettability is a prerequisite for a better understanding of oil/rock/brine interactions and for better application of enhanced oil recovery (EOR) techniques to increase recovery factors and improve the economic efficiency of field development. The nitrogen-, sulfur-, and oxygen-containing polar compounds in crude oil are key factors for sandstone wettability changes. In this study, an outcrop sandstone core selected from Jurassic formation in Sichuan Basin, China, was aged by crude oil to restore the wettability after being cleaned by hot Soxhlet extraction with an azeotropic solvent mixture of methanol and dichloromethane (MDC, vol/vol = 7:93). Then, Amott-Harvey experiments that were conducted by combining spontaneous imbibition and forced displacement steps of coreflooding were performed to characterize sandstone wettability after it was cut into four core blocks. The wettability index (IA-H) of four core blocks from the inlet to outlet of oil flooding were −0.523, 0.214, −0.087, and −0.861, respectively, which illustrated different degrees of sandstone wettability. The extracts of three sequential hot Soxhlet extraction steps of four core blocks were analyzed by gas chromatography-mass spectrometry (GC-MS) and high-resolution Fourier transform-ion cyclotron resonance-mass spectrometry (FT-ICR-MS) combined with electrospray ionization (ESI) in negative ion mode. Almost no polar compounds were detected in the n-hexane extracts, and a total of seven classes of different polar molecular compounds—namely, N1, N1O1, N1S1, O1, O2, O3, and O4—were detected in dichloromethane (DCM) and MDC extracts. The relative abundances of the N1S1 and O1 classes in the extracts of DCM and MDC were too low to be ignored. Compared to those of polar compounds in DCM extracts, the relative abundance of neutral nitrogen compounds (N1 and N1O1 classes) in the MDC extracts decreased significantly. In contrast, the acidic compounds (O2, O3, and O4 classes) all showed an obvious increase in the MDC extracts compared to the DCM extracts. It was notable that most of the polar compounds in MDC extracts were O2 and O3 compounds with double bond equivalent (DBE) values = 1 from the perspective of DBE distribution. The proportion of these two compound classes was much higher than that of all other polar compounds. Therefore, we believe that these two compound classes are the decisive factors for changing sandstone wettability combined with previous studies. In addition, based on the number of oxygen atoms and DBE values, we inferred that the O2 (DBE = 1) class was the long-chain saturated fatty acids and that the O3 (DBE = 1) class was the hydroxyl acids containing both one carboxyl and one hydroxyl group. Furthermore, the final determination of the wettability degree of the sandstone surface was the amount of all polar compounds, not only the relative abundance of these two types of acids. These two types of acids in crude oil were equivalent to anchor molecules on the surface of sandstone, and other polar compounds were adsorbed onto their surface to make the sandstone preferentially oil-wet.

Core-crosslinked micelles with a poly-anionic poly(styrene sulfonate)-based outer shell made by RAFT polymerization

Core-crosslinked micelles (CCMs) with a permanently charged anionic shell of sodium poly(styrene sulfonate) (PSS–Na+) chains have been developed by a convergent three-step one-pot RAFT polymerization starting with 4-cyano-4-thiothiopropylsulfanyl pentanoic acid (CTPPA, R0-SC(S)SnPr) as chain transfer agent, which includes polymerization-induced self-assembly (PISA) in the second step. The final crosslinking step of the R0-(SS-Na+)x-b-Sty-SC(S)SnPr diblock chains was carried out with diethylene glycol dimethacrylate (DEGDMA), either diluted into styrene (DEGDMA/St = 10:90) or neat. The morphology of the intermediate micelles and of the final CCM particles was studied by dynamic light scattering (DLS) and transmission electron microscopy (TEM) as a function of the relative degrees of polymerizations for the shell, core, and crosslinking blocks. Conformational instability was observed for the aqueous dispersions of the diblock micelles, especially with the shorter PSt blocks, yielding equilibria with single chains and large agglomerates. However, crosslinking led to well-defined CCMs with narrow size distributions for the optimized polymer compositions. The DLS analysis in a compatibilizing 60:40 THF/H2O solvent mixture demonstrates that the final step of the polymer synthesis has quantitatively crosslinked all diblock arms.